Circuit arrangement for compensating the aerial effect of directional antennae



T. W. LA RIVIERE CIRCUIT ARRANGEMENT FOR COMPENSATING THE AERIAL EFFECT OF DIRECTIONAL ANTENNAE Feb. 1,1949.

Filed/May l, 1946 v INVENTOR THEODOOR WILLEM LA RIVIERE Patented Feb. 1, 1949 CIRCUIT ARRANGEMENT FOR COMPENSAT- ING THE AERIAL EFFECT OF DIRECTION- AL ANTENNAE Theodoor Willem La Riviere, Eindhoven, Netherlands, assignor, by mesne assignments, to Hartford 'National Bank and Trust Company, Hartford, Conn as trustee Application May 1, 1946, Serial No. 666,249 In the Netherlands November 2-0, 1941 Section 1, Public Law 690, August 8, 1946 Patent expires November 20, 1961 It has been suggested before to compensate the aerial effect of directinal antennae by means of a compensation signal received in a non-directional manner and combined in the correct phase with the signal received in a directional manner.

With direction-finding receivers having directional antennae the measuring instruments and operating members are frequently arranged at a distance from the receiver proper so that it is also necessary for the above-mentioned compensation to be adjusted from a distance.

The invention has for its object to provide a circuit arrangement of the above-mentioned kind capable of being adjusted in a simple manner, in some cases from a distance.

According to the invention, the compensation signal is fed, with the interposition of a phaseshifting network, to a control electrode of a discharge tube having at least two output electrodes, the circuits of the output electrodes being coupled in opposite senses to an impedance to which the signal received in a directional manner is supplied in push-pull and from which the desired signal is derived, the current distribution between the two output electrodes being variable by variation of the bias voltage of one or more electrodes of the discharge tube.

In order that the invention may be clearly understood and readily carried into effect it will now be described more fully with reference to the accompanying drawing, in which one embodiment is illustrated.

Fig. 1 is the schematic diagram of a first preferred embodiment of the invention, and Fig. 2 illustrates a modification in the arrangement of Fig. 1.

Referring to the Figure 1 of the drawing, a rotatable loop antenna l is connected to the ends 2 and 4 of the primary of the input transformer of a receiver 5. The mid-point tapping 3 of the primary is earthed with the interposition of a condenser v(i. Owing to the aerial eifect of the loop antenna i the voltage supplied to the primary is not entirely equal to zero when the frame is arranged normally to the direction of incidence of the si nal. The direction of incidence of the signalis thus ascertained with greater difficulty.

order to obviate the diificulty the primary s'suppliedto it a compensation signal which is received bygmeans of anon-directional an- "tenna l. The antenna 1 is connected to earth via a resistance .8.

According to the invention, the voltage exist- .ing across the resistance 8 is supplied to a con- 5 Claims. (Cl. 343-113) 2 trol electrode of a pentode ii with the interposition of a phase-shifting network d, H).

The phase-shifting network comprises a resistance 9 and a condenser ii), the resistance being large compared with the impedance of the condenser so that the network brings about a phase-displacement of about The pentode i l comprises a cathode l2, a control grid IS, a screen grid l4, a suppressor grid I5 and an anode 6. The voltage existing across the condenser I6 is supplied to the control grid l3. The cathode lead of the tube ll includes the parallel combination of a resistance l1 and a condenser i8 which serves to generate the requ-ired negative bias,

The screen grid it is connected to the end ll and the anode .56 to the end 2 of the primary of the input transformer. The requisite positive bias for the anode and the screen grid is supplied through the mid-point tapping 3 via a resistance i9.

The suppressor grid l5 has supplied to it, through a conductor 26. a variable bias by means of which the compensation can be adjusted.

I The non-directional antenna '3 may be used at the same time for ascertaining the sense and for this purpose is connected to the receiver through a conductor 2|.

The operation of the circuit arrangement described is as follows. The anode current of the tube It brings about an alternating voltage across the top portion of the primary of the input transformer, which portion is comprised between the terminals 2 and 3. Similarly, the screen grid current brings about an alternating voltage across the bottom portion of the primary, which portion is comprised between the terminals 3 and t. The two alternating voltages mentioned are directed in opposite senses. Thus. if the bias of the suppressor grid i5 is so adjusted that the anode current is equally large as the screen grid current the two alternating voltages mentionedwiil neutralise each other so that no compensation is efiected at all. If the suppressor grid is made more positive the anode current will preponderate over the screen grid current so that a resulting compensation voltage of given phase is set up across the primary. Variation of the bias of the suppressor grid l5 therefore permits of regulating the value and the polarity of the compensation voltage existing in the primary so that full compensation of the aerial effect can be achieved at any time. The bias of the suppressor grid l5 can be adjusted in a simple manner from a distance with the aid of a potentiometer located near the operator.

Instead of having connected to them the ro-- tatable loop antenna l the ends 2 and 4 of the primary of the input transformer may have connected to them a searching coil which is coupled with two fixed directional antennae, for example the two loops set at right angles to each other.

This is illustrated in Fig. 2 which shows two perpendicularly arranged loop antennas 22 and 23 connected to the crossed field coils 2 2 and 25 of a conventional goniometer 26 whose search coil 2? is connected to the primary of the input transformer of receiver 5. The circuit is otherwise identical with that of Fig. 1.

I claim:

1. In a direction finding system having a directional antenna coupled across the input impedance of a radio receiver, an arrangement to compensate for aerial effect in said directional antenna comprising an amplifier circuit including an electron discharge device having a controi electrode and two output electrodes, one of said output electrodes being coupled to one end of said impedance and the other output electrode being coupled to the other end of said impedance whereby the currents flowing at the two output electrodes are applied to the impedance in opposing senses, a non-directional antenna, a phase shifting network, means to impress signals derived from said non-directional antenna through said network onto said control electrode, and means to vary the current distribution between the two output electrodes.

2. In a direction finding system having a directional antenna coupled across the input impedance of a radio receiver and a sense antenna coupled to said receiver, an arrangement to compensate for aerial effect in said directional antenna comprising an amplifier circuit including an electron discharge device having a control electrode and two output electrodes, one of said output electrodes being coupled'to one end of said impedance and the other output electrode being coupled to the other end of said impedance whereby the currents flowing at the two output electrodes are applied to the impedance in opposing senses, a phase shifting network, means to impress signals derived from the sense antenna through said network onto said control electrode, and means to vary the current distribution between the two output electrodes.

3. In a direction finding system having a pair of crossed directional antennas connected to the field coils of a goniometer, the search coil of the goniometer being connected across the primary of the input transformer of a radio receiver, an arrangement to compensate for aerial efiect in said directional antennas comprising an amplifier circuit including an electron discharge device having a control electrode and two out put electrodes, one of said output electrodes being connected to one end of said primary and the other of said output electrodes being connected to the other end of said primary whereby the output currents flowing at the two output electrodes are applied to said primary in opposing senses, a non-directional antenna, a phase shifting network, means to impress signals derived from said omni-directional antenna through said network onto said control electrodes, and means to vary the current distribution between the two output electrodes.

4. In a direction finding system having a directional antenna coupled across the center tapped input impedance of a radio receiver, an arrangement to compensate for aerial effect in said directional antenna comprising an amplifier circuit including an electron discharge tube having a cathode, a control grid, 3, screen grid, a suppressor grid and an anode, said screen grid being connected to one end of the input impedance and said anode being connected to the other end thereof, means to apply a positive potential I to the centertap of the impedance to energize said tube, means to apply an adjustable negative bias to said suppressor grid to vary thereby the current distribution between said screen grid and said anode, a non-directional antenna, a phaseshifting network, and means to impress signals derived from said non-directional antenna through said network onto said control grid.

5. In a direction finding system having a directional antenna coupled across a centertappedinput impedance of a radio receiver, an arrangement to compensate for aerial effect in said directional antenna comprising an amplifier circuit including an electron discharge device having a cathode, a control grid, a screen grid, a suppressor grid and an anode, said screen grid being connected to one end of said impedance, said anode being connected to the other end of said impedance, a cathode biasing resistor, a source of direct potential having its positive terminal connected to the centertap of said impedance and its negative terminal connected through said resistor to said cathode thereby to energize said device, means to apply an adjustable negative bias to said suppressor grid to vary thereby the current distribution between said screen grid and anode, a non-directional antenna, and a phase shifting network constituted by a resistance in series with a capacitance, the free end of said resistance being connected to said non-directional antenna and the free end of said capacitance being connected to the negative terminal of said source, the junction of said series-connected resistance and capacitance being connected to said control grid.

THEODOOR WILLEM LA RIVIERE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Date 1,702,440 Hinton Feb. 19, 1929 1,724,246 Wright et a1 Aug. 13, 1929 1,755,180 Herzog Apr. 22, 1930 1,868,982 Kroger July 26, 1932 1,955,267 Woods Apr. 17, 1934 

